Christina Eilers

The absorption lines in the Lyman-alpha (Ly$\alpha$) forest, seen in spectra of distant quasars and caused by patches of neutral hydrogen in the universe, has become an important tool for constraining cosmology and the intergalactic medium (IGM) at high-redshifts. Statistical properties of the transmitted flux in the Ly$\alpha$ forest such as the probability distribution function (PDF) or the one-dimensional power spectrum put constraints on the underlying physics of the IGM and the thermal evolution of our universe. Our goal is to compare the statistical properties of many high-resolution quasar spectra at redshifts of about $z\approx5-6$ to hydrodynamical simulations to obtain constraints on the cosmic ultra-violet background that is responsible for reionizing the universe and whose main origin and strength is still highly debated and on the thermal characteristics of the IGM which gives us insights about the onset and duration of the epoch of Hydrogen reionization.